Integrated circuit chips are usually mounted within ceramic or plastic housings so that they may be more easily handled and mounted to printed circuits boards.
The Plastic housings or packages are provided in two distinct varieties; i.e., post-molded and pre-molded.
In the post molded applications an IC chip is mounted upon a lead frame and the plastic package molded thereabout. In the pre-molded application, a plastic package is pre-formed; leads are attached thereto and formed to provide terminations; a chip is applied to the package, connections made; and a cover is applied to seal the package.
A prime example of the latter technique is shown in U.S. Pat. No. 4,653,174, which is assigned to the assignee of the instant invention, and the teachings of which are hereby incorporated by reference.
As noted in the above-described process, after the lead-ins, in the form of a segment, are attached to a package body, the outside terminal ends of the leads are formed to provide a suitable connector; e.g., a "J" lead, for making a surface mount contact with a printed circuit board. During this post forming of the lead-ins, the plastic package will be subjected to stress and occasional cracking as the metal frame is formed. There also is difficulty in holding dimensional accuracy of the lead-ins, and, the tooling required to hold the package, and the form punches themselves, are of a complex and sometimes flimsy design.